How Fade in UIButton

问题

how can I fade in a UIButton in a view?

now I add it with:

    [myView addSubview:myButton];

but if I want to fade it?

[UIView animateWithDuration:3.0
delay:0.0
options: UIViewAnimationCurveEaseInOut
animations:^{myButton.alpha = 1.0}
completion:^(BOOL finished){ [myView addSubview:myButton]; }];

Thanks!

回答1:

Try using

myButton.alpha = 0.0;
[myView addSubview:myButton];

prior to the animation call.

[UIView animateWithDuration:3.0
                      delay:0.0
                    options: UIViewAnimationCurveEaseInOut
                 animations:^{myButton.alpha = 1.0;}
                 completion:nil];

If you fade it in and add to view, the fading in part will not be within the bounds of the view (will be offscreen). So add it first at zero alpha and then fade it in.

回答2:

You should first add the view as a subview like you did with

 [myView addsubview:myButton];

Give it an alpha of 0.0 when you add it to your view. After that you should animate your button to an alpha value of 1.0

来源：https://stackoverflow.com/questions/6178531/how-fade-in-uibutton